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The present invention relates to centrifugal pumps for pumping liquids containing solids and in particular to a pump suited for use with clothes washing machines wherein long fiber solids may be encountered.
Pumps are used in washing machines to provide water pressure to transfer water through the machine during washing and to empty the machine after use. Dirt, extracted from the clothes, passes through the pump, as does larger debris released from the clothes including items contained in the pockets of the clothes such as toothpicks, paper clips, golf tees, coins, nails, screws and including loose clothing elements such as safety pins and buttons. With high efficiency washing machines, the relative concentration of such debris and dirt increases.
To some degree, passage of these large objects may be provided by increasing pump clearance. Alternatively, a filter may be placed in the water path, however, such filters must be cleaned regularly and can lead to service calls when the filter clogs by a consumer who may be unaware of the filter. A particular problem is long fiber solids such as strings, laces and threads that may entangle the pump rotor or which may xe2x80x9cropexe2x80x9d within the pump stopping or greatly reducing fluid flow.
The present invention provides an asymmetric, single-vane centrifugal pump, which has proven to significantly decrease roping so as to pass long fiber solids as well as compact debris.
Specifically, the present invention is a pump for a clothes washing machine of a type having a chamber for containing water and clothes, a chamber having an outlet so that the pump may pump water from the chamber between the inlet and outlet. The pump includes an electric motor having a shaft and a pump housing having a housing inlet connectable to the chamber outlet. The housing provides a pump volume receiving the motor shaft along an axis. A single vane impeller fitting within the pump volume and attached to the motor shaft may drive water from the housing inlet to the housing outlet with rotation of the motor shaft.
Thus it is one object of the invention to permit the pumping of long fiber solids in a washing machine with reduced risk of clogging.
The vane may subtend an angle of less than 270xc2x0 about an axis concentric with the motor shaft. Further, an edge of the vane closest to the motor shaft may be displaced radially from the motor shaft.
Thus it is another object of the invention to provide a vane construction that is believed to break up static vortices such as may promote roping and clogging by long fiber materials.
The vane may extend, in part, radially from an axis concentric with the motor shaft and a lip of the vane may taper at an end of the vane toward the motor shaft.
Thus it is another object of the invention to reduce points of entanglement with long fiber materials.
The vane may be constructed of an elastomeric material.
Thus it is another object of the invention to provide a vane that is resistant to impacts of entrained objects and to being jammed by materials lodged between the impeller and volute of the pump.
The impeller may project axially from a front surface of a backing disk extending radially from the motor shaft. The pump volume may be substantially cylindrical and the disk may extend to the cylindrical wall of the pump volume. Further, the pump housing may include a stationary vane extending radially and axially adjacent to a rear surface of the backing disk.
Thus it is another object of the invention to provide a design that resists the drawing in entanglement of fibers about the motor shaft. The stationary vane prevents the rotation of water such as might pull material behind the backer plate while the backer plate blocks the material generally.
The backing disk may include a counter weight balancing the backer disk and vane.
Thus it is another object of the invention to provide for smooth operation of the asymmetric vane design of the present invention.
The foregoing objects and advantages may not apply to all embodiments of the inventions and are not intended to define the scope of the invention, for which purpose claims are provided. In the following description, reference is made to the accompanying drawings, which form a part hereof, and in which there is shown by way of illustration, a preferred embodiment of the invention. Such embodiment also does not define the scope of the invention and reference must be made therefore to the claims for this purpose.